Device for converting electric oscillations into mechanical vibrations



Nov. 18, 1930. R. VERMEULEN ET AL 1,781,795

DEVICE FOR CONVERTING ELECTRIC OSCILLATIONS INTO MECHANICAL VIBRATIONS Filed May 18, 1927 a 9 I I I 1 3 xi l I l T F 1- l I ;l n l MINNIE \mmum &

\ :I/ \i 1% H INVENTOR ROELOF VERMEULEN AREND TNOMAS VAN URK I) 8 3 /2 BY THEODORUS m-mbmcus HERMANS /a(ma ATT RNEY k 4 and 5 in such a manner that 2 and 5, and- Patented Nov. 18, 1930 UNITED STATES PATENT OFFICE.

RoELoF VERMEULEN, AHREND THOMAS vim URK. AND rHEoDoRUs HENDRICUS HER- .MANs, OF EINDHOVEN, NETHERLANDS, ASSIGNORS ro RADIO CORPORATION on AMERICA; A CORPORATION on DELAwAnE DEVICE FOR CONVERTING ELECTRIC OSCILLA'I'IONS INTO MECHANICAL VIBRATION S Application filed May 18, 1927, Serial No. 192,430, and in the Netherlands May 21, 1926.

This inventionrefers to a device for converting electric oscillations into mechanical vibrations and more particularly for converting modulated electric currents into sound vibrations.

\The invention has for its object to provid an improved construction of such a device by which the sensibility is increased and natural vibrations of the component members are substantially reduced.

When rectilinear mechanical vibrations are to be produced or in particular when it is desired to generate sound vibrations, the simplest and at the same time the most satisfactory transfer of the vibrations of the armature to the sound producing membrane is ensured when the movements of the armature as well as the sound producing membrane are performed as perfectly straight line motions.

According to the invention the armature is adapted to move rectilinearly between two parallel but oppositely directed permanent magnetic fieldsand in the direction of these fields. The armature is secured to one or more laminated springs which support the armature between the permanent magnets and permit a suflicient'rectilinear movement of the armature. v

The invention will hereinafter be explained in greater detail by reference to the accompanying drawing which illustrates by way of example the invention adapted to a loudspeaker.

In the said drawing:

Figure 1 is a longitudinal section taken on the line I-I of Figure 2. p

Figure 2 is a lateral view.

Figure 3 is a cross-sectional view taken on the line TIL-III of Figure 2.

The legs of a permanent horse-shoe mag-Y net 1 have fixed to them four pole-shoes'2, 3,

3 and 4 respectively have the same polarity so that in the rathernar'row gaps between 2'and 4 and between 3 and 5 respectively,

oppositely directed fields are brought about. 'Within these gaps a soft iron armature 6 is adapted to move but only in the direction of the force lines. If this armature is midway in the two said gaps it is evidently in unstable equilibrium as it is attracted with an equal force by the two pairs of poles 2, 3 and 4, 5 respectively. As soon, however, as a magneto-motoric force is applied within the armature the equilibrium is broken and the armature is attracted either by 2 and 3 or transferred by means of two small rods 8 and.

a yoke 9 to a small rod 10 that acts on the membrane (cone or similar member). In order that the armature may always recede from every position to the neutral position, the two ends of the armature are secured to-the centres of two laminated springs 11. Either one or both ends of the spring are clamped by screws 12. 1

Owing to the fact that'the members 6, 8, 9 and 10 all perform perfectly rectilinear reciprocating movements no forces of torsion are produced in them and therefore resonant influences due to the natural oscillations of these elements of the mechanism are avoided.

What we claim is: y 1. A device for converting electrical oscillations into mechanical vibrations compris ing a permanent magnet, pole pieces for said magnet providing two north poles and'two south poles, a fiat armature positioned between the poles of said pole pieces, said pole pieces being so constructed and arranged that there is one north pole'and one south pole below and above the armature, members connected to, the ends ofsaid armature, a yoke connecting said members, an operating rod connected to said yoke, and acoil surrounding said armature, said coil being adapted to carry a voice-modulated current to vary the magnetic force between the magnet .pole pieces and the armature.

2. A device of the character described com prising a frame, a magnet, an armature in the field of the magnet, a coil around the armature, and two springs fastened at their ends to the frame, the ends of the armature being fastened to the centers of the springs.

3. A device according to claim 1, including in addition thereto two springs, the armature being fastened to the centers of the springs, and means for supporting the ends of said springs, saidmeans being secured to said magnet.

H ROELOF VERMEULEN.

AREND THOMAS van URK. THEODORUS HENDRICUS HERMANS. 

